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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/53073] [4.8 Regression] 464.h264ref in SPEC CPU 2006 miscompiled
Date: Thu, 31 Jan 2013 09:29:00 -0000	[thread overview]
Message-ID: <bug-53073-4-FV84c2FTt2@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-53073-4@http.gcc.gnu.org/bugzilla/>


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53073

--- Comment #12 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-01-31 09:28:28 UTC ---
FYI, regarding validity in C89, the wording there is similar to C99.
ISO C89, 6.3.1.2 says that d[++k] is equivalent to:
  (*((d)+(++k)))
and ++k in the last iteration is 16, so it is
  (*(d+16))
and then 6.3.6 part applies:
"Unless both the pointer operand and the result point to elements of the
same array object, or the pointer operand points one past the last element  
of an array object and the result points to an element of the same array
object, the behavior is undefined if the result is used as an operand of the 
unary * operator."
Here the pointer operand points to the first element of array (&d[0]) and
the result points one past the last element of the array object, so again, the
behavior is undefined.


      parent reply	other threads:[~2013-01-31  9:29 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-04-22 17:11 [Bug middle-end/53073] New: " hjl.tools at gmail dot com
2012-04-23  9:21 ` [Bug middle-end/53073] " rguenth at gcc dot gnu.org
2012-04-23 11:30 ` rguenth at gcc dot gnu.org
2012-04-23 11:44 ` rguenth at gcc dot gnu.org
2012-08-21  6:28 ` venkataramanan.kumar at amd dot com
2012-11-08 10:42 ` pinskia at gcc dot gnu.org
2013-01-15 17:02 ` mpaton at swbell dot net
2013-01-15 17:56 ` jakub at gcc dot gnu.org
2013-01-15 20:01 ` mpaton at swbell dot net
2013-01-28 18:51 ` sje at gcc dot gnu.org
2013-01-29  9:11 ` rguenther at suse dot de
2013-01-31  9:01 ` rguenth at gcc dot gnu.org
2013-01-31  9:29 ` jakub at gcc dot gnu.org [this message]

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